Australian Prime Minister Tony Abbott said his government's treatment of a boatload of 157 Sri lankan asylum-seekers who have been kept at sea for weeks would underline its resolve to stop people-smuggling.

Abbott, who came to power in September promising to "stop the boats" bringing asylum-seekers from countries such as Iran and Afghanistan, said Canberra would not dodge its international and legal obligations.

But he said the boat carrying the group of 157 -- thought to be mostly minority ethnic Tamils from Sri Lanka -- now being brought to the Australian mainland would demonstrate Canberra's position.

Abbott stressed that those who come to Australia illegally by boat will "never ever get permanent residency".